The "dry eye syndrome" DES is a highly prevalent ocular disease, in particular in the elderly population. One mainstay of therapy for patients suffering from DES is the use of topically administered lubricants. However, despite many efforts, no "ideal" formulation has yet been found.

Recently, Croma Pharma has introduced chitosan-N-acetylcysteine eye drops, designed for treatment of symptoms related to DES. Chemically, chitosan is a polycationic biopolymer with favourable biological properties such as high biocompatibility and low toxicity. Additionally, the new formulation comprises N-acetylcysteine, which has been used in ophthalmology because of its mucolytic properties for several years. Based on theoretical considerations, one can hypothesize that the new chitosan derivative may show an increased adhesion to mucins of the ocular surface and may therefore be particularly beneficial in reducing the symptoms associated with DES. We have recently shown in a phase I trial that single instillation of chitosan-N-acetylcysteine eye drops is well tolerated in young healthy subjects.

However, no data is yet available about safety and tolerability of chitosan-N-acetylcysteine in subjects wearing contact lenses. This is of special interest because the tear film is critical to successful contact lens wear. Disturbances of the quantity or quality of the tear film results in intolerance of contact lens wear and possible damage to the ocular surface. This trial seeks to investigate the local tolerability and possible ocular discomfort of chitosan-N-acetylcysteine eye drops after repeated instillation .

The medical test device will be administered with the contact lenses inserted

Device: Chitosan-N-acetylcysteine eye drops (concentration of 0.1%)

1 drop of the medical device in 1 randomly chosen eye

Other: Physiological saline solution

1 drop as placebo in the other eye not receiving the medical device

Experimental: 12 subjects wearing rigid contact lenses

The medical test device will be administered with the contact lenses inserted

Device: Chitosan-N-acetylcysteine eye drops (concentration of 0.1%)

1 drop of the medical device in 1 randomly chosen eye

Other: Physiological saline solution

1 drop as placebo in the other eye not receiving the medical device

Experimental: 12 subjects with soft contact lenses

The medical test device will be administered before insertion of the contact lenses

Device: Chitosan-N-acetylcysteine eye drops (concentration of 0.1%)

1 drop of the medical device in 1 randomly chosen eye

Other: Physiological saline solution

1 drop as placebo in the other eye not receiving the medical device

Experimental: 12 subjects with rigid contact lenses

The medical test device will be administered before insertion of the contact lenses

Device: Chitosan-N-acetylcysteine eye drops (concentration of 0.1%)

1 drop of the medical device in 1 randomly chosen eye

Other: Physiological saline solution

1 drop as placebo in the other eye not receiving the medical device

Eligibility

Ages Eligible for Study:

18 Years and older (Adult, Senior)

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

Regular contact lens wear since 3 years minimum

Daily wearing time of the contact lens of 8 hours or more

Good tolerability of the contact lenses without ocular discomfort or local signs of chemosis, conjunctival redness or other signs of intolerability as judged by the investigator.

Subject willing to continue contact lens use for the study period

Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant

Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant

Normal ophthalmic findings except ametropia

Exclusion Criteria:

Participation in a clinical trial in the 3 weeks preceding the study

Use of colored contact lenses

Abuse of alcoholic beverages or other drugs

Symptoms of a clinically relevant illness in the 3 weeks before the first study day

Pregnancy

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01747616